Processor, modem and method for cancelling alien noise in coordinated digital subscriber lines

Abstract

A method of cancelling alien noise in coordinated DSL lines, a method of smoothing an alien noise covariance estimate, and a processor and modem for cancelling alien noise in coordinated DSL lines. In one embodiment, the method of cancelling alien noise includes: (1) estimating alien noise vectors for at least some training symbols, (2) arranging the alien noise vectors in a matrix dimensioned for a number of coordinated DSL lines, (3) orthonormally transforming the matrix into a lower-triangular matrix and (4) computing alien noise prediction filters from the lower-triangular matrix.

Description

CROSS-REFERENCE TO RELATED APPLICATION[0001]This application claims the benefit of U.S. Provisional Application Ser. No. 61 / 348,042, filed by Al-Dhahir, et al., on May 25, 2010, entitled “Alien Noise Cancellation Method for Coordinated DSL Lines,” commonly assigned with this application and incorporated herein by reference.U.S. GOVERNMENT LICENSE RIGHTS[0002]This invention was made with U.S. Government support under National Science Foundation SBIR Grant No. 1047336. The U.S. Government has certain rights in the invention.TECHNICAL FIELD[0003]This application is directed, in general, to a digital communications system and, more specifically, to interference reduction in the context of Digital Subscriber Line (DSL) lines.BACKGROUND[0004]Alien noise, also known as out-of-domain interference, in a DSL cable binder is due to crosstalk (both far-end, or FEXT, and near-end, or NEXT) from non-coordinated lines within the same binder or from adjacent binders. The coordinated lines within a ...

AI Technical Summary

Problems solved by technology

Non-idealities in the in-domain crosstalk cancellation result in residual self FEXT between the coordinated lines, which is an additional component to the alien noise, potentially limiting the performance in the system.

If left uncompensated, alien noise can diminish any performance gains realized by self FEXT cancellation.

The LMS technique is iterative, suboptimal and often slow to converge, whereas the systems requiring the noise cancellation, such as cellular backhaul systems, typically do not permit extended latencies and cannot afford iterative or slow-converging solutions for noise cancellation.

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